Lasers have been utilized for some time in eye surgery for delivering short bursts of high energy coherent light. They have proved useful in various eye operations such as capsulotomies and vitreous removals. Unlike other surgical techniques utilizing lasers, eye surgery requires that the laser be focused on a portion of the eye that is interior to the cornea. In so doing, it is necessary to expand the laser beam prior to entering the surface of the cornea and then focus it on the other side of the cornea interior to the eye itself. In this manner, the destructive energy of the laser is only focused at a certain point on the interior surface of the eye or on a point within an area of the eye such as the lens.
In addition to delivering the laser energy internal to the eye, it is also necessary for a surgeon to very carefully locate the point at which the laser beam focuses since even a slight deviation in positioning of the laser beam prior to cutting can be disastrous. For example, if the laser beam were to accidentally be focused on the macula of the eye, a patient could be permanently blinded. It is therefore necessary for a surgeon to have adequate control over the power level of the laser in addition to having the capability of finely positioning the focal point of the laser such that this positioning is both reliable and accurate in addition to possessing a high degree of stability.
Since positioning is of paramount importance, it is necessary to utilize a system that delivers the laser energy within the viewing area of the surgeon. The surgeon can utilize either an opthalmoscope or, more commonly, a slit lamp which is comprised of a biomicroscope for viewing the eye and a slit lamp for rotation about the periphery of the eye for illumination thereof. In present systems, the laser is delivered through optics along the viewing axis of the biomicroscope such that the surgeon can locate the area to be operated upon and then activate the laser to perform the actual surgery. Since the viewing axis is normally perpendicular to the eye, this can have disastrous effects in that the sensitive portions of the eyes, such as the macula, are in close proximity thereto. For example, when operating upon cataracts, it is possible for the laser to accidently impinge upon the macula. These types of systems have no capability for delivering the laser along any path other than the viewing axis.
The type of laser utilized for surgery depends upon the particular operation. For operations that coagulate tissue, a laser emitting in the green region is normally utilized since red tissue absorbs heavily in the green region. In other applications, however, an infrared laser is utilized to deliver large amounts of power. It has been necessary in prior art systems to have separate lasers available to generate the particular frequencies that are found most useful in the surgical process.
In view of the above disadvantages with the prior art in positioning a laser for surgical use, it is desirable to provide a laser delivery system for ophthalmic use that provides laser energy that is not perpendicular to the eye and also has the versatility of outputting a multiplicity of frequencies or wavelengths.